Auto merge of #91195 - camelid:path-did, r=jyn514

rustdoc: Remove `ResolvedPath.did`

`ResolvedPath.did` was not actually the same as `.path.def_id()`. Instead,
`.did` referred to the `DefId` of the page to be used as a hyperlink target.
For example, a link to `Struct::method()` would use `Struct`'s `DefId` as its
`.did` field. This behavior is confusing, easy to accidentally misuse, and can
instead be obtained on-demand when computing hyperlink targets. It's also likely
part of the reason `kind_side_channel` exists. I'm currently working on some
experimental refactorings in `collect_intra_doc_links` that I believe require --
or at least benefit from -- removing `.did`.

r? `@jyn514`

src/librustdoc/clean/mod.rs

@@ -1411,12 +1411,12 @@ impl<'tcx> Clean<Type> for Ty<'tcx> {
                 };
                 inline::record_extern_fqn(cx, did, kind);
                 let path = external_path(cx, did, false, vec![], substs);
-                ResolvedPath { path, did }
+                ResolvedPath { path }
             }
             ty::Foreign(did) => {
                 inline::record_extern_fqn(cx, did, ItemType::ForeignType);
                 let path = external_path(cx, did, false, vec![], InternalSubsts::empty());
-                ResolvedPath { path, did }
+                ResolvedPath { path }
             }
             ty::Dynamic(obj, ref reg) => {
                 // HACK: pick the first `did` as the `did` of the trait object. Someone

src/librustdoc/clean/types.rs

@@ -1419,7 +1419,7 @@ crate enum Type {
     /// A named type, which could be a trait.
     ///
     /// This is mostly Rustdoc's version of [`hir::Path`]. It has to be different because Rustdoc's [`PathSegment`] can contain cleaned generics.
-    ResolvedPath { path: Path, did: DefId },
+    ResolvedPath { path: Path },
     /// A `dyn Trait` object: `dyn for<'a> Trait<'a> + Send + 'static`
     DynTrait(Vec<PolyTrait>, Option<Lifetime>),
     /// A type parameter.
@@ -1522,7 +1522,7 @@ impl Type {
 
     fn inner_def_id(&self, cache: Option<&Cache>) -> Option<DefId> {
         let t: PrimitiveType = match *self {
-            ResolvedPath { did, .. } => return Some(did),
+            ResolvedPath { ref path } => return Some(path.def_id()),
             DynTrait(ref bounds, _) => return Some(bounds[0].trait_.def_id()),
             Primitive(p) => return cache.and_then(|c| c.primitive_locations.get(&p).cloned()),
             BorrowedRef { type_: box Generic(..), .. } => PrimitiveType::Reference,

src/librustdoc/clean/utils.rs

@@ -187,7 +187,8 @@ crate fn build_deref_target_impls(cx: &mut DocContext<'_>, items: &[Item], ret:
             for &did in prim.impls(tcx).iter().filter(|did| !did.is_local()) {
                 inline::build_impl(cx, None, did, None, ret);
             }
-        } else if let ResolvedPath { did, .. } = *target {
+        } else if let ResolvedPath { path } = target {
+            let did = path.def_id();
             if !did.is_local() {
                 inline::build_impls(cx, None, did, None, ret);
             }
@@ -360,8 +361,8 @@ crate fn resolve_type(cx: &mut DocContext<'_>, path: Path) -> Type {
         Res::SelfTy(..) if path.segments.len() == 1 => Generic(kw::SelfUpper),
         Res::Def(DefKind::TyParam, _) if path.segments.len() == 1 => Generic(path.segments[0].name),
         _ => {
-            let did = register_res(cx, path.res);
-            ResolvedPath { path, did }
+            let _ = register_res(cx, path.res);
+            ResolvedPath { path }
         }
     }
 }
@@ -393,20 +394,12 @@ crate fn register_res(cx: &mut DocContext<'_>, res: Res) -> DefId {
     debug!("register_res({:?})", res);
 
     let (did, kind) = match res {
-        Res::Def(DefKind::AssocTy | DefKind::AssocFn | DefKind::AssocConst, i) => {
-            // associated items are documented, but on the page of their parent
-            (cx.tcx.parent(i).unwrap(), ItemType::Trait)
-        }
-        Res::Def(DefKind::Variant, i) => {
-            // variant items are documented, but on the page of their parent
-            (cx.tcx.parent(i).expect("cannot get parent def id"), ItemType::Enum)
-        }
-        // Each of these have their own page.
+        // These should be added to the cache using `record_extern_fqn`.
         Res::Def(
             kind
             @
-            (Fn | TyAlias | Enum | Trait | Struct | Union | Mod | ForeignTy | Const | Static
-            | Macro(..) | TraitAlias),
+            (AssocTy | AssocFn | AssocConst | Variant | Fn | TyAlias | Enum | Trait | Struct
+            | Union | Mod | ForeignTy | Const | Static | Macro(..) | TraitAlias),
             i,
         ) => (i, kind.into()),
         // This is part of a trait definition; document the trait.

src/librustdoc/formats/cache.rs

@@ -401,8 +401,8 @@ impl<'a, 'tcx> DocFolder for CacheBuilder<'a, 'tcx> {
             clean::ImplItem(ref i) => {
                 self.cache.parent_is_trait_impl = i.trait_.is_some();
                 match i.for_ {
-                    clean::ResolvedPath { did, .. } => {
-                        self.cache.parent_stack.push(did);
+                    clean::ResolvedPath { ref path } => {
+                        self.cache.parent_stack.push(path.def_id());
                         true
                     }
                     clean::DynTrait(ref bounds, _)
@@ -436,9 +436,9 @@ impl<'a, 'tcx> DocFolder for CacheBuilder<'a, 'tcx> {
             // Note: matching twice to restrict the lifetime of the `i` borrow.
             let mut dids = FxHashSet::default();
             match i.for_ {
-                clean::ResolvedPath { did, .. }
-                | clean::BorrowedRef { type_: box clean::ResolvedPath { did, .. }, .. } => {
-                    dids.insert(did);
+                clean::ResolvedPath { ref path }
+                | clean::BorrowedRef { type_: box clean::ResolvedPath { ref path }, .. } => {
+                    dids.insert(path.def_id());
                 }
                 clean::DynTrait(ref bounds, _)
                 | clean::BorrowedRef { type_: box clean::DynTrait(ref bounds, _), .. } => {

src/librustdoc/html/format.rs

@@ -13,8 +13,10 @@ use rustc_attr::{ConstStability, StabilityLevel};
 use rustc_data_structures::captures::Captures;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_hir as hir;
+use rustc_hir::def::DefKind;
 use rustc_hir::def_id::DefId;
 use rustc_middle::ty;
+use rustc_middle::ty::DefIdTree;
 use rustc_middle::ty::TyCtxt;
 use rustc_span::def_id::CRATE_DEF_INDEX;
 use rustc_target::spec::abi::Abi;
@@ -502,7 +504,16 @@ crate fn href_with_root_path(
     cx: &Context<'_>,
     root_path: Option<&str>,
 ) -> Result<(String, ItemType, Vec<String>), HrefError> {
-    let cache = &cx.cache();
+    let tcx = cx.tcx();
+    let def_kind = tcx.def_kind(did);
+    let did = match def_kind {
+        DefKind::AssocTy | DefKind::AssocFn | DefKind::AssocConst | DefKind::Variant => {
+            // documented on their parent's page
+            tcx.parent(did).unwrap()
+        }
+        _ => did,
+    };
+    let cache = cx.cache();
     let relative_to = &cx.current;
     fn to_module_fqp(shortty: ItemType, fqp: &[String]) -> &[String] {
         if shortty == ItemType::Module { fqp } else { &fqp[..fqp.len() - 1] }
@@ -751,8 +762,9 @@ fn fmt_type<'cx>(
 
     match *t {
         clean::Generic(name) => write!(f, "{}", name),
-        clean::ResolvedPath { did, ref path } => {
+        clean::ResolvedPath { ref path } => {
             // Paths like `T::Output` and `Self::Output` should be rendered with all segments.
+            let did = path.def_id();
             resolved_path(f, did, path, path.is_assoc_ty(), use_absolute, cx)
         }
         clean::DynTrait(ref bounds, ref lt) => {

src/librustdoc/html/render/cache.rs

@@ -371,7 +371,7 @@ crate fn get_real_types<'tcx>(
             let mut ty_generics = Vec::new();
             for bound in bound.get_bounds().unwrap_or(&[]) {
                 if let Some(path) = bound.get_trait_path() {
-                    let ty = Type::ResolvedPath { did: path.def_id(), path };
+                    let ty = Type::ResolvedPath { path };
                     get_real_types(generics, &ty, tcx, recurse + 1, &mut ty_generics, cache);
                 }
             }

src/librustdoc/html/render/mod.rs

@@ -1227,8 +1227,8 @@ fn should_render_item(item: &clean::Item, deref_mut_: bool, tcx: TyCtxt<'_>) ->
             | SelfTy::SelfExplicit(clean::BorrowedRef { mutability, .. }) => {
                 (mutability == Mutability::Mut, false, false)
             }
-            SelfTy::SelfExplicit(clean::ResolvedPath { did, .. }) => {
-                (false, Some(did) == tcx.lang_items().owned_box(), false)
+            SelfTy::SelfExplicit(clean::ResolvedPath { path }) => {
+                (false, Some(path.def_id()) == tcx.lang_items().owned_box(), false)
             }
             SelfTy::SelfValue => (false, false, true),
             _ => (false, false, false),
@@ -2520,7 +2520,7 @@ fn collect_paths_for_type(first_ty: clean::Type, cache: &Cache) -> Vec<String> {
         }
 
         match ty {
-            clean::Type::ResolvedPath { did, .. } => process_path(did),
+            clean::Type::ResolvedPath { path } => process_path(path.def_id()),
             clean::Type::Tuple(tys) => {
                 work.extend(tys.into_iter());
             }

src/librustdoc/html/render/print_item.rs

@@ -727,10 +727,11 @@ fn item_trait(w: &mut Buffer, cx: &Context<'_>, it: &clean::Item, t: &clean::Tra
         let mut implementor_dups: FxHashMap<Symbol, (DefId, bool)> = FxHashMap::default();
         for implementor in implementors {
             match implementor.inner_impl().for_ {
-                clean::ResolvedPath { ref path, did, .. }
-                | clean::BorrowedRef {
-                    type_: box clean::ResolvedPath { ref path, did, .. }, ..
-                } if !path.is_assoc_ty() => {
+                clean::ResolvedPath { ref path }
+                | clean::BorrowedRef { type_: box clean::ResolvedPath { ref path }, .. }
+                    if !path.is_assoc_ty() =>
+                {
+                    let did = path.def_id();
                     let &mut (prev_did, ref mut has_duplicates) =
                         implementor_dups.entry(path.last()).or_insert((did, false));
                     if prev_did != did {

src/librustdoc/json/conversions.rs

@@ -365,8 +365,7 @@ impl FromWithTcx<clean::GenericBound> for GenericBound {
         match bound {
             TraitBound(clean::PolyTrait { trait_, generic_params }, modifier) => {
                 // FIXME: should `trait_` be a clean::Path equivalent in JSON?
-                let trait_ =
-                    clean::ResolvedPath { did: trait_.def_id(), path: trait_ }.into_tcx(tcx);
+                let trait_ = clean::ResolvedPath { path: trait_ }.into_tcx(tcx);
                 GenericBound::TraitBound {
                     trait_,
                     generic_params: generic_params.into_iter().map(|x| x.into_tcx(tcx)).collect(),
@@ -391,9 +390,9 @@ impl FromWithTcx<clean::Type> for Type {
     fn from_tcx(ty: clean::Type, tcx: TyCtxt<'_>) -> Self {
         use clean::Type::*;
         match ty {
-            ResolvedPath { path, did } => Type::ResolvedPath {
+            ResolvedPath { path } => Type::ResolvedPath {
                 name: path.whole_name(),
-                id: from_item_id(did.into()),
+                id: from_item_id(path.def_id().into()),
                 args: path.segments.last().map(|args| Box::new(args.clone().args.into_tcx(tcx))),
                 param_names: Vec::new(),
             },
@@ -436,7 +435,7 @@ impl FromWithTcx<clean::Type> for Type {
             },
             QPath { name, self_type, trait_, .. } => {
                 // FIXME: should `trait_` be a clean::Path equivalent in JSON?
-                let trait_ = ResolvedPath { did: trait_.def_id(), path: trait_ }.into_tcx(tcx);
+                let trait_ = ResolvedPath { path: trait_ }.into_tcx(tcx);
                 Type::QualifiedPath {
                     name: name.to_string(),
                     self_type: Box::new((*self_type).into_tcx(tcx)),
@@ -502,10 +501,7 @@ impl FromWithTcx<clean::Impl> for Impl {
         let provided_trait_methods = impl_.provided_trait_methods(tcx);
         let clean::Impl { unsafety, generics, trait_, for_, items, polarity, kind } = impl_;
         // FIXME: should `trait_` be a clean::Path equivalent in JSON?
-        let trait_ = trait_.map(|path| {
-            let did = path.def_id();
-            clean::ResolvedPath { path, did }.into_tcx(tcx)
-        });
+        let trait_ = trait_.map(|path| clean::ResolvedPath { path }.into_tcx(tcx));
         // FIXME: use something like ImplKind in JSON?
         let (synthetic, blanket_impl) = match kind {
             clean::ImplKind::Normal => (false, None),